So the orgy was a bit of a retcon of Moka's characters, but the way they had sex and the ending (the one we're supposed to get) are basically what I expected. If we gliss over the fact that the orgy event is pure fanservice (and that, in this regard, it “bends” the consistency of the manga’s final part), overall this is one of the best erotica manga works ever to come out of Japan, in fact it doesn't have any asspull or any hentai sheningans that usually end up fucking the whole story over.
So this author is one of the first to have succeeded in creating something worthwhile with this type of manga.